`default-chain.ts` — canonical detector-chain factory

(no submodules)

Purpose

defaultDetectorChain(options) builds the canonical 8-or-9 entry detector chain consumed by <TranslationProvider> and useLocaleDetection (and any other chain consumer that wants a sensible default without enumerating every detector). The factory returns a fresh LocaleDetector[] on every call so callers can mutate or filter the result without affecting subsequent invocations.

The order is deliberate: explicit user signals (querystring, backend preference, cookie, localStorage) come first, followed by shell-rendered hints (htmlLang), browser preferences (acceptLanguage, navigator), geolocation (cloudflareIpGeo), and finally the unconditional fallback.

Features

8-entry chain when userPreferenceEndpoint is omitted; 9-entry chain when it is supplied. The user-preference detector slots in second so authenticated users' saved preferences beat every device-bound signal.
Fresh array per call — callers can .filter / .splice / .concat without affecting subsequent invocations.
Fallback always last; the factory wires fallbackDetector(options.fallback) as the terminal entry.
Every detector is constructed with default options — consumers that need custom names / paths / endpoints assemble their own chain.

Usage: Basic Example

import {
    createDetectorChain,
    defaultDetectorChain,
} from "@suaveplan/i18n-detector";

const chain = createDetectorChain(
    defaultDetectorChain({ fallback: "en-GB" })
);

Usage: Advanced Example

import {
    createDetectorChain,
    defaultDetectorChain,
} from "@suaveplan/i18n-detector";

const chain = createDetectorChain(
    defaultDetectorChain({
        fallback: "en-GB",
        userPreferenceEndpoint: "/api/me/locale",
    }),
    { throwOnExhausted: true }
);

// Or filter to remove a detector that does not fit the deployment.
const detectors = defaultDetectorChain({ fallback: "en-GB" }).filter(
    (d) => d.name !== "cloudflareIpGeo"
);

API Reference

defaultDetectorChain(options): LocaleDetector[] — fresh array per call.
DefaultDetectorChainOptions.fallback: string — required.
DefaultDetectorChainOptions.userPreferenceEndpoint?: string — enables the user-preference detector when set.

Implementation Notes

The fallback is constructed via fallbackDetector(...) which validates the locale at chain-build time, so a misconfigured fallback surfaces immediately rather than at the first request.
The factory makes no assumptions about cookie name, storage key, querystring param name, or geolocation header. Consumers that need custom configuration assemble their own chain by importing each detector directly.

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default-chain.ts — canonical detector-chain factory